a case of sporadic hypokalemic periodic paralysiswith sinus bradycardia

background & objective:  periodic paralyses are a group of rare disorders that cause temporary episodes of muscle weakness or paralysis.  hypokalemic periodic paralysis usually is transmitted by an autosomal dominant trait with more penetration in men.  hypokalemic periodic paralysis may be secondary to thyrotoxicosis, hyperparathyroidism, drug  toxicity and potassium losing states. sporadic form of disease is rare and appears in male gender. case report: this case is a 34 years old man with history of periodic paralysis.  there was  hypokalemia (k=1.98meq/lit), but other laboratory tests and paraclinical data were normal. first electrocardiogram had st segment depression, negative t wave and positive u wave with sinus bradycardia (heart rate was  45 beats per minute). changes discussion: of st segment, t wave and u wave are common but sinus bradycardia is rare. limb paralysis and electrocardiogram changes disappeared with ingestion of 6 gram kcl. therefore in hypokalemic periodic paralysis cardiac arrhythmia can appear as sinus bradycardia that disappears with administration of  oral potassium. cardiac evaluations using ecgs and monitoring should be performed on all hospitalized patients with hypokalemic periodic paralysis .